The present invention relates to an intake manifold having a structure in which branch passages are wound around a collector, for an internal combustion engine, and more particularly to an intake manifold formed as an integral unit by vibration-welding a plurality of synthetic resin-made members.
As disclosed in Japanese Unexamined Patent Publications No. 2008-106628 (hereinafter is referred to as “JP2008-106628”) and No. 2015-048814 (hereinafter is referred to as “JP2015-048814”), there has been known an intake manifold (called a branch passage-winding-type intake manifold) having a structure in which a plurality of branch passages are formed so as to wind around an outer periphery of a collector that extends along a direction of a line of cylinders. Such type of intake manifolds have been proposed and developed to secure a long length of the branch passage in limited outer dimensions of the intake manifold. As disclosed in these publications, as a typical manner of producing the intake manifold, a plurality of synthetic resin-made members partly forming the collector and the branch passages etc. are combined and joined or fixed together by vibration-welding.
The collector of the intake manifold could be provided with a connector passage for connecting the collector and an external pipe, for instance, for taking out a negative pressure from an inside of the collector or for introducing a certain gas (such as an EGR gas and a blowby gas) into the collector.
Japanese Unexamined Patent Publication No. 2013-249732 (hereinafter is referred to as “JP2013-249732”) has disclosed a synthetic resin-made intake manifold having a structure in which a plurality of branch passages extend from a collector to a side of the collector, and also disclosed that a connector passage is formed along a mating surface of two synthetic resin-made members that are welded together. More specifically, the connector passage is not connected to a collector body part that is covered or wound with the branch passages, but connected to an inlet port of a collector end portion that is not covered or overlapped with the branch passages.